@Dxerty: Please explain a little better. The automatic sorting of bookmarks is ALREADY "Manually." Where are you having problems? (Please be sure to differentiate between Bookmarks Bar, Bookmarks Panel, and Bookmarks Editor (page linked from Speed Dial).

@Dxerty: Are you aware that you can set automatic sort for both the panel and the manager, and still have manual sort in the bookmarks bar and the speed dial? That's how I have it. Without any extension. Manual is of course the opposite of automatic. If you sort manually, nothing will happen automatically. If you sort automatically, you will not be able to move anything to a different sort order. If you right-click on the bookmarks bar, you get to select how it will be sorted. If you click on the "sort" bar at the top of the bookmark panel, you will get to select how that is sorted. If you click at the top of any column in the Bookmarks manager (page accessed from Speed Dial), it will sort by that column. What more, exactly do you need? (and if you use an extension to sort, it will disable Vivaldi's sorting).

Yes, but it remains inadequately functioning, unfortunately. As many users have pointed out for a long time, its [Manager] Title auto sort [still] intermixes folders/subfolders & individual sites, when it alphabetically sorts. It needs to be able to place folders/subfolders [duly sorted] ahead of sites [duly sorted], if that's the user's preference. This ongoing shortcoming is why i continue to need the extension, hence why i recommended it to the OP.